Empty set differs from NULL is that you get an empty set if you apply an element-wise function over it (which most operators and functions in EdgeQL are).

> Why not just use an Option/Maybe type?

We are considering adding algebraic types and a syntax to match them, but it ultimately boils down to taste and use case:

  SELECT value ?? "fallback in case of empty"

is not fundamentally different from (hypothetical):

  SELECT 
    MATCH value
    CASE Some(non_empty_val) THEN non_empty_val
    CASE Empty THEN "fallback in case of empty"
    END;